Ensure no String-based class-lookup is needed for DateFormatSymbols.getInstance at libgraal runtime

Author: olpaw

compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/LibGraalSubstitutions.java

@@ -24,14 +24,18 @@
  */
 package jdk.graal.compiler.libgraal;
 
+import java.text.DateFormatSymbols;
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Set;
 
 import com.oracle.svm.core.annotate.Alias;
 import com.oracle.svm.core.annotate.RecomputeFieldValue;
 import com.oracle.svm.core.annotate.Substitute;
 import com.oracle.svm.core.annotate.TargetClass;
 
+import jdk.graal.compiler.debug.DebugOptions;
+
 class LibGraalSubstitutions {
 
     @TargetClass(className = "jdk.vm.ci.services.Services", onlyWith = LibGraalFeature.IsEnabled.class)
@@ -103,4 +107,18 @@ static Class<?> findBootstrapClassOrNull(String name) {
             return null;
         }
     }
+
+    @TargetClass(value = java.text.DateFormatSymbols.class, onlyWith = LibGraalFeature.IsEnabled.class)
+    static final class Target_java_text_DateFormatSymbols {
+        /*
+         * DateFormatSymbols.getInstance(Locale) relies on String-based class-lookup (to find
+         * resource bundle sun.text.resources.cldr.FormatData) which we do not want to rely on at
+         * libgraal runtime because it increases image size too much. Instead, we return the
+         * DateFormatSymbols instance that we already have in the image heap.
+         */
+        @Substitute
+        public static DateFormatSymbols getInstance(Locale unused) {
+            return DebugOptions.getSharedDateFormatSymbols();
+        }
+    }
 }

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/debug/DebugOptions.java

@@ -30,6 +30,7 @@
 import static jdk.graal.compiler.debug.PathUtilities.getPath;
 
 import java.io.IOException;
+import java.text.DateFormatSymbols;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 
@@ -324,6 +325,20 @@ public static String getDumpDirectory(OptionValues options) throws IOException {
         return dumpDir;
     }
 
+    /**
+     * This circumvents instantiating SimpleDateFormat at libgraal runtime. This is needed to avoid
+     * String-based class-lookup (to find resource bundle sun.text.resources.cldr.FormatData as part
+     * of SimpleDateFormat construction) and allows us to avoid class-lookup support in the image.
+     */
+    private static final SimpleDateFormat SIMPLE_DATE_FORMAT = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss.SSS");
+
+    public static DateFormatSymbols getSharedDateFormatSymbols() {
+        // SimpleDateFormat is not thread-safe
+        synchronized (SIMPLE_DATE_FORMAT) {
+            return SIMPLE_DATE_FORMAT.getDateFormatSymbols();
+        }
+    }
+
     /**
      * Returns the {@link #getDumpDirectory} without attempting to create it.
      */
@@ -333,8 +348,12 @@ public static String getDumpDirectoryName(OptionValues options) {
             dumpDir = getPath(DumpPath.getValue(options));
         } else {
             Date date = new Date(GraalServices.getGlobalTimeStamp());
-            SimpleDateFormat formatter = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss.SSS");
-            dumpDir = getPath(DumpPath.getValue(options), formatter.format(date));
+            // SimpleDateFormat is not thread-safe
+            String dateString;
+            synchronized (SIMPLE_DATE_FORMAT) {
+                dateString = SIMPLE_DATE_FORMAT.format(date);
+            }
+            dumpDir = getPath(DumpPath.getValue(options), dateString);
         }
         dumpDir = getAbsolutePath(dumpDir);
         return dumpDir;